Optical device comprising a light source (4) emitting a light beam according to a maximum emission direction defining an axis Z, and a bimaterial lens. The bimaterial lens comprises an internal volume (6) with a first material with a first refractive index and an external volume (5) with a second material with a second refractive index, both volumes being separated by an interface surface (1). The first refractive index is higher than the second refractive index. The internal volume (6) is defined by the interface surface (1), a lower surface (2), and an upper surface (3). The interface surface (1) is a surface other than a surface defined by a single equation, does not have symmetry of revolution, and/or the curve obtained from the intersection of the interface surface (1) with a plane containing the maximum emission direction has at least one inflection point.